EXPLICIT TIME OF ADVANCE FORMULA FOR FURROW DESIGN

The behavior of the dimensionless advance curves obtained numerically for .various values of infiltration parameter is systematically analyzed. It was found that when the advance problem is expressed in terms of new variables conveniently selected, the various advance curves can be described by a single curve independent of infiltration parameter. A simple, explicit, time of advance formula that fits the single curve previously reported is derived. Comparison tests indicate that when an adjusted shape factor for the surface profile is used, the predictions of the proposed formula are in agreement with accurate kinematic wave numerical solutions. An optimal design procedure for furrow irrigation using the above formula is presented.